It is known to use coating compositions curable by high-energy radiation in automotive coating. Coating compositions based on free-radically polymerizable binders are in particular used in such applications. The following are advantages of radiation-curable coating compositions: very short curing times, low solvent emission of the coating compositions and good hardness and scratch resistance of the resulting coatings.
Prior art processes are known in which coated foils are applied onto the substrate, for example, an automotive body. The foils may here be provided on one side with one or more coating layers and may have on the same or the other side an adhesive layer so that the foil can be fixed to the substrate. Where appropriate binders are used, the coating and/or adhesive layers may also be cured by ultraviolet light (UV) radiation. Such foils and corresponding application processes are described, for example, in WO-A-00/08094, WO-A-00/63015, EP-A-251 546 and EP-A-361 351. In general, the foil is laminated onto the substrate, where it remains fixed to the substrate.
DE-A-196 54 918, U.S. Pat. No. 5,912,081 and U.S. Pat. No. 6,221,439 describe coating foils which are so-called free coating films. The coating foils comprise an adhesive layer and at least one coating layer. It is possible to dispense with a stabilizing backing foil in these cases.
WO 00/78847 describes free foils, which once applied onto appropriate substrate surfaces, are heated and/or irradiated with actinic radiation; the nature of the foils is described by means of physical parameters, while the material composition thereof remains largely unexplained. The physical behaviour of the foils may be adjusted by, for example, incorporating components into conventional and known foils, which components, on the one hand, act as plasticizers and, on the other, may be cured with actinic radiation or be removed from the foil, for example by vaporization.
It is desirable to find a way to be able to apply coatings of radiation-curable coating compositions without using conventional types of application, such as, for example, spray application. The use of adhesive layers or of backing layers, such as, for example, backing foils, which remain on the substrate should also be avoided.